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    SubjectRe: [PATCH] Revert "spi: omap2-mcspi: Set FIFO DMA trigger level to word length"
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    CC: OMAP list for good measure

    On 1/13/19 2:49 PM, David Lechner wrote:
    > This reverts commit b682cffa3ac6d9d9e16e9b413c45caee3b391fab.
    >
    > That commit breaks displays using tinydrm drivers, such as ili9225.
    >
    > It causes corruption in the image that is displayed (it looks like only
    > 1/2 of the framebuffer data is sent, the other half of the display
    > remains blank.)
    >
    > The following error appears multiple times:
    >
    > ili9225 spi1.0: EOW timed out
    >
    > Eventually, the system locks up without any additional errors.
    >
    > Cc: Vignesh R <vigneshr@ti.com>
    > Signed-off-by: David Lechner <david@lechnology.com>
    > ---
    > drivers/spi/spi-omap2-mcspi.c | 26 +++++++++++++++++++-------
    > 1 file changed, 19 insertions(+), 7 deletions(-)
    >
    > diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
    > index 2fd8881fcd65..5a3854ff2e08 100644
    > --- a/drivers/spi/spi-omap2-mcspi.c
    > +++ b/drivers/spi/spi-omap2-mcspi.c
    > @@ -306,7 +306,7 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
    > struct omap2_mcspi_cs *cs = spi->controller_state;
    > struct omap2_mcspi *mcspi;
    > unsigned int wcnt;
    > - int max_fifo_depth, bytes_per_word;
    > + int max_fifo_depth, fifo_depth, bytes_per_word;
    > u32 chconf, xferlevel;
    >
    > mcspi = spi_master_get_devdata(master);
    > @@ -322,6 +322,10 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
    > else
    > max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH;
    >
    > + fifo_depth = gcd(t->len, max_fifo_depth);
    > + if (fifo_depth < 2 || fifo_depth % bytes_per_word != 0)
    > + goto disable_fifo;
    > +
    > wcnt = t->len / bytes_per_word;
    > if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT)
    > goto disable_fifo;
    > @@ -329,17 +333,16 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
    > xferlevel = wcnt << 16;
    > if (t->rx_buf != NULL) {
    > chconf |= OMAP2_MCSPI_CHCONF_FFER;
    > - xferlevel |= (bytes_per_word - 1) << 8;
    > + xferlevel |= (fifo_depth - 1) << 8;
    > }
    > -
    > if (t->tx_buf != NULL) {
    > chconf |= OMAP2_MCSPI_CHCONF_FFET;
    > - xferlevel |= bytes_per_word - 1;
    > + xferlevel |= fifo_depth - 1;
    > }
    >
    > mcspi_write_reg(master, OMAP2_MCSPI_XFERLEVEL, xferlevel);
    > mcspi_write_chconf0(spi, chconf);
    > - mcspi->fifo_depth = max_fifo_depth;
    > + mcspi->fifo_depth = fifo_depth;
    >
    > return;
    > }
    > @@ -598,6 +601,7 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
    > struct dma_slave_config cfg;
    > enum dma_slave_buswidth width;
    > unsigned es;
    > + u32 burst;
    > void __iomem *chstat_reg;
    > void __iomem *irqstat_reg;
    > int wait_res;
    > @@ -617,14 +621,22 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
    > }
    >
    > count = xfer->len;
    > + burst = 1;
    > +
    > + if (mcspi->fifo_depth > 0) {
    > + if (count > mcspi->fifo_depth)
    > + burst = mcspi->fifo_depth / es;
    > + else
    > + burst = count / es;
    > + }
    >
    > memset(&cfg, 0, sizeof(cfg));
    > cfg.src_addr = cs->phys + OMAP2_MCSPI_RX0;
    > cfg.dst_addr = cs->phys + OMAP2_MCSPI_TX0;
    > cfg.src_addr_width = width;
    > cfg.dst_addr_width = width;
    > - cfg.src_maxburst = es;
    > - cfg.dst_maxburst = es;
    > + cfg.src_maxburst = burst;
    > + cfg.dst_maxburst = burst;
    >
    > rx = xfer->rx_buf;
    > tx = xfer->tx_buf;
    >

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